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Effects of food and ectoparasites on age of natal dispersal in burrowing owls

Effects of food and ectoparasites on age of natal dispersal in burrowing owls. and. Courtney J. Conway. Victoria Garcia. University of Arizona. Photo by D. Hearne. Dispersal and evolution. Photo by John Cocanower. Photo by Cagan H. Sekercioglu. Migration. Cooperative breeding.

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Effects of food and ectoparasites on age of natal dispersal in burrowing owls

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  1. Effects of food and ectoparasiteson age of natal dispersal in burrowing owls and Courtney J. Conway Victoria Garcia University of Arizona Photo by D. Hearne

  2. Dispersal and evolution Photo by John Cocanower Photo by Cagan H. Sekercioglu Migration Cooperative breeding Inbreeding avoidance

  3. Dispersal and populations Population dynamics Population genetics

  4. Dispersal and fitness Photo by D. Hearne Image by Bobbie Peachey Survival Reproduction

  5. Movement between natal site and first breeding site (Greenwood 1980) When to disperse? Natal dispersal

  6. Natal dispersal timing disperse as soon as possible disperse as late as possible When to disperse?

  7. Burrowing owls (Athene cunicularia) Vary in age at which initiate natal dispersal (~45 d to >110 d) Why?

  8. What causes variation in age of natal dispersal in burrowing owls?

  9. Sunny Walter sunny@sunnywalter.com

  10. Methods

  11. Study site 6,500km2 area in eastern Washington

  12. Study population • Mostly migratory • 2 cavity nesters • Cache prey in burrow • Juveniles fly well ~40d

  13. Food abundance natal dispersal?Ectoparasite load natal dispersal? 2 treatments to nests:

  14. Mice supplements 50% energetic needs (95g/owl/week) Flea removal diatomaceous earth powder & water solution powder for dust baths Nests treated weekly, 14d to dispersal

  15. Determining dispersal age • transmittered 67 juveniles • re-located 3x/week until seen >300m from nest >1 visit • dispersal age from hatch date

  16. Effect of diatomaceous earth on ectoparasite load Trapped and banded juveniles Assigned index of flea load (0-5)

  17. Statistical analysis • effect of treatments on dispersal age • effect of diatomaceous earth on flea load • two-way ANOVA for a completely randomized design with factorial treatment

  18. Results and Discussion

  19. Juvenile fate

  20. n = 35 Sample size by treatment

  21. Food abundance P = 0.027

  22. Ectoparasites P = 0.065

  23. Effect of diatomaceous earth on fleas P = 0.65 1.23 1.17

  24. Effect of food supplements on fleas P = 0.019

  25. Flea load and dispersal age P = 0.41

  26. Summary 1. Food supplements earlier dispersal 2. Food supplements flea load 3. Flea load dispersal age 4. Diatomaceous earth later dispersal 5. Diatomaceous earth flea load

  27. Future directions • treatments juvenile weight • juvenile weight dispersal age • food supplements number fledged • local food abundance dispersal age • diatomaceous earth avian ectoparasites

  28. Acknowledgments BLM (Spokane), Columbia NWR, Washington Dept of Fish and Wildlife Field crew: Lisa Ellis, Joey Jarrell, Rick Keck, Aimee Mitchell, Chris Nadeau, Emily Sullivan Landowners in eastern Washington Lab group: Alice Boyle, Katie Hughes, Matt Smith, Allyson Wheelock

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